Lal9: Star Properties and the Hertzsprung-Russell Diagram Objectives: e Compare luminosity, mass, color, and size between the nearest and the brightest stars in the sky e Analyze what type of stars are most common e Understand what properties determine how bright a star is e Understand the difference between possible and probable star properties Name: Lab partner(s): Date: Note: graphs are 15 points each: 10 points for correctly plotting the points in the x and y axes; 5 points for color and size being correct/accurate. Take the time to do the graphs carefully Toolkit You need to represent four (4) things all at once for each star! 1. What radius it has this affects how big of a circle you'll draw to represent it: Radius > 300x as Radius >100x Radius>10xas Radius>2xas Radius like Super big as the sun as big as the sun pig as the sun big as the sun the sun small 2. What color the star would look like through a telescope. Use the color given in this Spectral Sequence data table based on the star's temperature: THE SPECTRAL SEQUENCE Class Spectrum Color Temperature ionized and neutral helium, weakened hydrogen bluish 31,500-49,000 K neutral helium, stronger hydrogen blue-white 10,000-31,500 K strong hydrogen, ionized metals white 7500-10,000 K weaker hydrogen, ionized metals yellowish white 6000-7500 K still weaker hydrogen, ionized and neutral metals yellowish 5300-6000 K weak hydrogen, neutral metals orange 3800-5300 K little or no hydrogen, neutral metals, molecules reddish 2100-3800 K The star's brightness or luminosity. You can find this in the third column of each of the star data tables below The star's temperature. This is in the second column of each of the star data tables below. Your job is to make TWO separate versions of the HR diagram we discussed in class with the TWO different populations of stars below. Then you will compare the information you find as a result. DO NOT * Do not connect your datapoints with lines * Do NOT try to write down the name of every star where the star is located. Represent each star with a circle as described in the toolkit. * Do not write down the data that you used to position each point, either. The datapoint should represent all the information you need * Do not use Excel to make these plots. Place each point by hand (a tablet is acceptable. A program like Microsoft Paint is acceptable. A drawing by hand is acceptable if it is legible) Plot 1: The fakest example stars EXAMPLE: You can do circles instead of stars Luminosity [Lq,,] Spectral Type Part 1: The 25 Nearest Stars to the Sun Name Temperature Luminosity Radius Mass (K) (# x L_sun) (# x R_sun) (# x M_sun) Sun 5800 1 1 1 Proxima Centauri 3000 0.001 0.15 0.1 Alpha Centauri A 5800 1.5 1.2 1.1 Alpha Centauri B 5200 0.5 0.9 0.9 Barnard's Star 3100 0.004 0.2 0.1 Wolf 359 2800 0.001 0.15 0.1 Lalande 21185 3800 0.02 0.4 0.5 Sirius A 9900 25 1.7 2 Sirius B 25200 0.06 0.01 1 Luyten 726-8 2700 0.0001 0.15 0.1 Ross 154 3300 0.004 0.24 0.2 Ross 248 2800 0.002 0.16 0.1 Epsilon Eridani 5100 0.3 0.75 0.8 Lacaille 9352 3600 0.03 0.45 0.5 Ross 128 3200 0.004 0.21 0.15 EZ Aquarii 2700 0.001 0.1 0.1 Procyon A 6500 7 2 1.5 Procyon B 7700 0.0005 0.01 0.6 61 Cygni A 4500 0.08 0.6 0.63 Struve 2398A 3400 0.04 0.35 0.3 Groombridge 34 3700 0.03 0.38 0.4 Epsilon Indi 4600 0.2 0.73 0.8 DX Cancri 2800 0.0007 0.11 0.1 Tau Ceti 5300 0.5 0.8 0.8 Gliese 1061 2800 0.001 0.1 0.1Part 1 (15 pts): Graph the 25 nearest stars on this diagram. Use colors that correspond to their temperature, and draw circles that roughly match their sizes relative to the sun Hertzsprung-Russell Diagram of the 25 nearest stars BRIGHTNESS (x Sun) 100,000 10,000 1,000 100 10 1 0.1 0.01 0.001 20000 8000 4500 30,000 10,000 6000 3000 TEMPERATURE (K) Part 2: The 25 Brightest Stars in the Sky Name Temperature Luminosity Radius Mass (K) (# of L_sun) (# of R_sun) (# of M_sun) Sun 5800 1 1 Sirius 9900 25 1.7 N Canopus 7400 12000 71 10 Alpha Centauri 5800 1.5 1.2 1.1 Arcturus 4300 170 26 1.1 Vega 9600 50 2.8 2.1 Capella 4900 79 12 2.7 Rigel 11000 80000 80 20 Procyon 6500 7 2 1.5 Achernar 15000 3000 11 7 Betelgeuse 3500 140000 1180 8 Hadar 25000 41000 8 11 Acrux 28000 25000 4 10 Altair 7700 11 1.8 1.8 Aldebaran 3900 500 44 1.7 Antares 3400 58000 880 12 Spica 22000 12000 7 10 Pollux 4900 43 8 2 Fomalhaut 8750 18 2 2 Becrux 27000 34000 8 16 Deneb 8500 200000 200 19 Regulus 10000 290 3 4 Adhara 22000 39000 14 12 Castor 10000 30 2.3 2.2 Gacrux 3600 1500 84 1.3Part 2 (15 points): Graph the 25 brightest stars on this diagram. Use colors that correspond to their temperature, and draw circles that roughly match their sizes relative to the sun Hertzsprung-Russell Diagram of the 25 brightest stars BRIGHTNESS (x Sun) 100,000 10,000 1,000 100 0.01 0.001 20000 8000 4500 30,000 10,000 6000 3000 TEMPERATURE (K) Part 3: Consider the graphs and data 1. (5 points) Study and compare the colors, sizes, luminosities, and masses represented by the data to answer the following questions: A. Summarize the properties of the brightest stars in the night sky: B. Summarize the properties of the nearest stars: 2. (3 pts) Given your answers for the previous questions, what kinds of stars are nOot common in our solar neighborhood? Include a description of at least 3 properties that identify them: Stars that are are hard to find in our solar neighborhood 3. (3 pts) In contrast, which stars ARE common in our solar neighborhood? Again, include at least 3 properties: Stars that are are commonly found near the sun. Part 3: Consider the graphs and data 6. (6 pts) Pick a property (color, temperature, mass, OR luminosity). Count how many stars (of the 50 in both lists) fall into the category of more property than the sun, and how many fall into the category of less property than the sun. (For example, radius; stars that have a bigger radius than the sun, and stars that have a smaller radius than the sun). A. Property you chose: B. How many stars fall into the more category? C. How many stars fall into the less category? D. (2 pts) How do your results change if you use three categories instead: more, less, and about the same ? (3 pts) One of the concepts astronomers use to think about the universe is called the Copernican principle (which is sometimes presented as part of the Cosmological principle). This assumes that: \"humans, on the Earth or in the Solar System, are not privileged observers of the universe, that observations from the Earth are representative of observations from the average position in the universe.\" (Wikipedia, retrieved 11/1/2022. Copernican Principle, https://en.wikipedia.org/wiki/Copernican_principle) If that assumption is correct, and our solar neighborhood is not a special neighborhood in the galaxy, then which kinds of stars are very common not just in our solar neighborhood but throughout the galaxy --and indeed in other galaxies that are similar to our own